C# Stats Functions Example

using System;
using System.Collections;

using CenterSpace.NMath.Core;
using CenterSpace.NMath.Stats;

namespace CenterSpace.NMath.Stats.Examples.CSharp
{
  /// <summary>
  /// A .NET example in C# showing how to use the descriptive statistics functions of the
  /// StatsFunctions class.
  /// </summary>
  class StatsFunctionsExample
  {

    static void Main(string[] args)
    {
      // Read in data from a comma-delimited file. Data has age, gender, grade
      // columns.

      // Specify the data file, whether it includes headers, whether it has row keys,
      // the delimiter, and whether to try to parse data into non-generic types.
      DataFrame data = DataFrame.Load("..\\..\\StatsFunctionsExample.dat", true, false, ",", true);

      // Print out all data.
      Console.WriteLine();
      Console.WriteLine(data);
      Console.WriteLine();

      // Print out top grade
      Console.WriteLine("highest grade.. " + StatsFunctions.MaxValue(data["Grade"]));
      Console.WriteLine();

      // How many male and female students are there?
      IDictionary counts = StatsFunctions.Counts(data["Gender"]);
      Console.Write("There are " + counts["Male"] + " male students and ");
      Console.WriteLine(counts["Female"] + " female students.");
      Console.WriteLine();

      // Mean, median, mode grades
      Console.WriteLine("mean grade: " + StatsFunctions.Mean(data["Grade"]));
      Console.WriteLine("median grade: " + StatsFunctions.Median(data["Grade"]));
      Console.WriteLine("most common grade: " + StatsFunctions.Mode(data["Grade"]));
      Console.WriteLine();

      // Is there a correlation between age and grade?
      double correlation = StatsFunctions.Correlation(data["Age"], data["Grade"]);
      if (correlation > 0.0)
      {
        Console.WriteLine("There is a positive correlation of " + correlation + " between age and grade.");
        Console.WriteLine();
      }

      // What percentage of students pass with a 50% passing rate?  60%?
      Console.WriteLine("Percentage passing with 50% cutoff: " + System.Math.Round(((1.0 - StatsFunctions.PercentileRank(data["Grade"], 50)) * 100.0), 2) + "%");
      Console.WriteLine("Percentage passing with 60% cutoff: " + System.Math.Round(((1.0 - StatsFunctions.PercentileRank(data["Grade"], 60)) * 100.0), 2) + "%");
      Console.WriteLine();

      // Percentiles
      Console.WriteLine("Interquartile range is " + StatsFunctions.InterquartileRange(data["Grade"]));
      Console.WriteLine("What's the 80th percentile? " + StatsFunctions.Percentile(data["Grade"], 0.8));
      Console.WriteLine();

      // Split by gender and do descriptive statistics
      Factor gender = data.GetFactor("Gender");
      Subset[] genderGroups = Subset.GetGroupings(gender);
      for (int i = 0; i < genderGroups.Length; i++)
      {
        DataFrame genderSpecific = data.GetRows(genderGroups[i]);
        Console.WriteLine(gender.Levels[i] + " students...");
        Console.WriteLine("mean grade: " + System.Math.Round(StatsFunctions.Mean(genderSpecific["Grade"]), 2));
        Console.WriteLine("median grade: " + StatsFunctions.Median(genderSpecific["Grade"]));
        Console.WriteLine("most common grade: " + StatsFunctions.Mode(genderSpecific["Grade"]));
        Console.WriteLine();
      }

      // Young students
      DataFrame young = data[new Subset(StatsFunctions.If(data["Age"], new StatsFunctions.LogicalDoubleFunction(Young))), Slice.All];
      Console.WriteLine("Young students...");
      Console.WriteLine("mean grade: " + System.Math.Round(StatsFunctions.Mean(young["Grade"]), 2));
      Console.WriteLine("median grade: " + StatsFunctions.Median(young["Grade"]));
      Console.WriteLine("most common grade: " + StatsFunctions.Mode(young["Grade"]));
      Console.WriteLine();

      // Top grade by a young student?
      double top = StatsFunctions.MaxValue(young["Grade"]);
      Console.WriteLine("Top grade by a young student was... " + top);

      // What percentage of the whole group beat the top-ranked young student?
      Console.WriteLine("Percentage beating top-ranked young student... " + System.Math.Round(((1.0 - StatsFunctions.PercentileRank(data["Grade"], top)) * 100.0), 2) + "%");

      Console.WriteLine();
      Console.WriteLine("Press Enter Key");
      Console.Read();

    }  // Main

    private static bool Young(double age)
    {
      return age < 20.0;
    }

  }  // class

}  // namespace